The present disclosure relates to a vehicle fuel system, and particularly to a fuel vapor venting system associated with a vehicle fuel tank. More particularly, the present disclosure relates to fuel vapor recovery canisters included in fuel vapor venting systems.
Vehicle fuel systems are configured to vent pressurized or displaced fuel vapor from the vapor space in the fuel tank to a separate charcoal canister. The canister is designed to capture and store hydrocarbons entrained in fuel vapors that are displaced and generated in the fuel tank and then discharge filtered air from the canister to the atmosphere. More specifically, during venting, hydrocarbons carried in the fuel vapor are stored (e.g., adsorbed) on charcoal held in the canister.
Fuel vapor is vented from the fuel tank into the canister during fuel tank refueling when a vehicle engine is off as the incoming fuel displaces fuel vapor within the fuel tank. In addition, fuel vapor is frequently vented from the fuel tank during normal operation of the vehicle fuel system as a consequence of daily rising atmospheric temperatures around the fuel tank that cause expansion of fuel and fuel vapor stored in the fuel tank.
A purge vacuum is applied to the canister when the vehicle engine is running via an engine intake manifold coupled to the canister. Hydrocarbons stored on charcoal held in the canister are entrained in a stream of atmospheric air drawn into the canister by the purge vacuum. This produces a stream of fuel vapor laden with reclaimed hydrocarbon material that is discharged through a purge hose into the intake manifold for combustion in the engine.